1. Field of the Invention
The present invention relates to an electronic circuit for the performing of a monostable switching function in a bistable relay through the conversion of binary input signals into control signals for the bridge switching circuit consisting of two bridge branches with complementary operating electronic switches, whereby the flow direction of the current is reversible in the relay through intermediary of the bridge switching circuit, and the relay is switchable at each change in the level of the input signal through a pulse with a predetermined energy content.
2. Discussion of the Prior Art
Control circuits of that type are currently known in the technology. For instance, in U.S. Pat. No. 4,455,587, which is assigned to the common assignee of the present application, there is described an electronic control circuit of that type in which a bistable relay performs a monostable switching function. In this control circuit, control pulses which are adapted for a bridge circuit are generated through the intermediary of a relatively complex logic circuit, which presently connects the exciter windings of the bistable relay for the duration of the control pulse with the two poles of a voltage source. This will then determine the flow direction of the current through the exciter windings by means of an input signal which is applied to the electronic circuit.
Moreover, the electronic control circuit disclosed in U.S. Pat. No. 4,455,587 possesses further special capabilities, such as the pulse-synchronous switching of the relay, or also the formation of special "regenerating pulses".
However, there is also currently evident a need for simpler circuits which serve exclusively for the performing of a monostable switching function in a bistable relay, especially for the purpose of savings in energy.
A circuit of that type is also described in the data sheet of the SDS-Electro GMBH concerning its Module IC-12 V, or respectively, IC-24 V. Hereby, a bistable relay is connected in series with a capacitor, wherein the capacitor must be of such size that the capacitance of the capacitor produces a charging time constant, in conjunction with the winding resistance of the relay, which at least as large as the response time of the relay. Obtained thereby, particularly in the control of relays with a high switching rating (pursuant to the data sheet, page 2), capacitance values of up to a few hundred microfarads.